1. Field of the Invention
The present invention relates to an overload protector, and more particularly, to an overload protector with a hermetically sealing structure capable of protecting an insulating solution (e.g., varnish) from permeating into the interior thereof when a winding of a target (e.g., a motor) to which the overload protector is mounted is immersed into an insulating solution to insulate the winding.
2. Description of the Related Art
In general, overload protectors are used in the following: a motor protector for protecting a motor from over-current; a ballast applied with a high voltage to preheat and light a fluorescent lamp, and a transformer for transforming a high voltage to a microwave oven, so as to prevent a target from overload.
Such an overload protector is classified into an internal type and an external type according to the mounting mode thereof. The internal-type overload protector is directly connected a winding of the motor, ballast, or transformer. Since the winding consists of thin and fine wires arranged densely, the winding is generally immersed into an insulating solution such as varnish, so as to place the wiring at a proper position and to insulate the wirings. At that time, since the internal-type overload protector is already built in the target, the overload protector is also immersed in the insulating solution.
The possible permeation of the insulating solution into the overload protector during the immersing process causes the internal circuit of the protector to become inoperable, so that an article with a built-in overload protector may not be protected from overload.
Accordingly, the present invention is directed to an overload protector that substantially obviates one or more problems due to limitations and disadvantages of the related art.
It is an object of the present invention to provide an overload protector with an improved hermetically sealed structure capable of protecting a foreign substance such as an insulating solution from permeating into the interior thereof.
To achieve these objects and other advantages in accordance with the purpose of the invention as embodied and broadly described herein, an overload protector with a hermetically sealed structure is provided. The overload protector comprises: a housing that has an outer peripheral flange and an external connecting terminal, and that accommodates a bimetal element having a movable contact and a fixed contact; a conducting plate that is installed to an upper portion of the housing, and that has an external connecting terminal and a contact connected to the movable contact of the bimetal element; and an insulating gasket disposed between the housing and the conducting plate, wherein grooves or ribs are formed on the entire flange, and ribs or grooves are formed on a portion of the conducting plate corresponding to the grooves or ribs formed on the flange in such a way that the ribs or grooves of the conducting plate are engaged with the grooves or ribs of the flange.
According to one preferred embodiment of the present invention, the insulating gasket contains a resin, and during the assembly of the overload protector, the resin molten at a thermosetting process is hardened around the grooves or ribs formed at the flange of the housing, thereby improving sealing capability. Preferably, the resin is a polyamide-based resin.
The insulating gasket is formed with a through-hole through which the movable contact of the bimetal element is in contact with the contact of the conducting plate.
The insulating gasket includes bending portions formed in a longitudinal direction thereof for fixing the conducting plate during the assembly step of the overload protector.
The housing includes bending portions formed in a longitudinal direction thereof for fixing the gasket and the conducting plate during the assembly step of the overload protector.
The housing includes two protruded contacts each making contact with the movable and fixed contacts of the bimetal element.
The overload protector of the present invention may be used in an electric appliance, which generates heat at activation, such as a motor, a ballast for a fluorescent lamp, a transformer, and so forth.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.